Bell (126) made the same score – unbeaten last time – as in his only previous century, on this same ground five years ago, in a total of 288 for six in the first NatWest Series match at the Ageas Bowl.
West Indies' own substitute opener Dwayne Smith (56) then gave England plenty to think about – pulling his second six, off Stuart Broad, to go with six fours and bring up his 50 in only 38 balls – but his power-packed team-mates failed to deliver, bowled out for 172 with more than 14 overs unused.
Bell, opening for the first time since last year's World Cup, produced a chanceless innings of trademark timing and placement – with 12 fours and one six from 117 balls – after England were put in under cloudy skies.
His performance, and that of number three Jonathan Trott, who made 42 and combined with the Warwickshire batsman for a stand of 108, drew praise from captain Alastair Cook.
"It was a really good performance from the lads and Ian at the top of the order was fantastic, especially under cloudy conditions to start with," Cook said of the man who has never been able to nail down a place in England's one-day side.
"He and Trotty played really well and 288, I think we would have taken that at the toss."
Referring to the opener's role vacated by Pietersen's limited overs retirement, the Essex batsman added: "We've had to move on from KP but what a great performance from Ian at the top of the order.
"A fantastic knock and when you get close to 300 in any ground, it's hard to chase."
On a very good batting surface, by the time Bell mis-timed an attempted "paddle" at a slow full-toss from Dwayne Bravo, to loop a simple catch and become wicketkeeper Denesh Ramdin's fourth victim of the day, England were in prime position to attack the last 10 overs.
The only complicating factor was that five wickets were down already, but Craig Kieswetter and the tail made sure that dwindling resources did not compromise the addition of 68 more runs.
Bell was passed fit, for his first assignment as Pietersen's successor, having on Friday edged a pull into his face in indoor practice – a mishap which resulted in 10 stitches and an X-ray on his jawbone. He showed no ill-effects, in a match minus West Indies' destructive opener Chris Gayle – a surprise absentee with a shin injury.
England were almost instantly without their captain as Cook departed to the third ball of the match, from Ravi Rampaul, pushing forward and edging a modicum of movement behind.
However, Bell and Trott's second-wicket stand partnership put them in good shape. The latter, and Ravi Bopara, were lost in near identical fashion, but Bell ensured an opener reached three figures in each of England's last five ODI innings, only to lose Eoin Morgan – playing on to Marlon Samuels at the start of the batting powerplay – and then go himself at the end of it.
West Indies opener Lendl Simmons chopped James Anderson down on to his stumps. But Smith, in place of Gayle, took a huge pulled six and two fours from one Steve Finn over to give the tourists' run chase early momentum in a half-century stand with Ramdin.
After Tim Bresnan (four for 34) eliminated the second-wicket pair in the space of five balls, however, Smith edging a very short ball behind and Ramdin lbw, Finn hit Darren Bravo in front too.
Kieron Pollard cut Broad hard to point – where Morgan took a flying catch – and in the absence of specialist batsman Bravo, who injured his groin in the field, from 127 for five the West Indies' remaining power hitters had far too much to do.
They returned from an hour-long rain break with a revised target of 287 in the 25 overs still available – but after Samuels fell to a chip to midwicket, West Indies' miserable day was soon complete.